1. Field of the Invention
The present invention relates to methods and systems for filtering electronic messages, such as used to detect “spam” messages delivered to an electronic address.
2. Description of Related Art
Unsolicited commercial email, sometimes called “spam,” is a persistent problem for operators and users of email systems. Despite the introduction of various message-filtering technologies, a substantial amount of spam continues to be generated and delivered to many users. Spam filters often employ very sophisticated algorithms for application to message content to determine whether a particular message should be classified as spam. Almost as quickly as these filters evolve and learn, spam generators develop new messages that can pass through existing spam filters. At the same time, legitimate email is sometimes incorrectly classified as spam by message filters, which may lead to damaging communications failures.
There is also the problem of distinguishing between legitimate, appropriate commercial solicitations, and illegitimate spam. Legitimate commercial offers are not unwelcome for most users, and may be part of systems for financing content and network resources providers. Such messages are not indiscriminately generated and do not create undue burdens for email users and systems. Illegitimate spam, in contrast, tends to be generated indiscriminately and is virtually always unwanted by the recipient.
It is desirable, therefore, to provide an improved message filtering method that overcomes the limitations of the prior art. The method should be capable of integrated application with existing filtering methods, or as a stand-alone application.